On a Friday morning four years ago, Lenny dropped off his son, Noah, at Sandy Hook Elementary School in Newtown, Conn. It was three weeks after Noah's sixth birthday, and he had just lost his first tooth. He was a little guy, bright and inquisitive, who loved books and started reading at an early age.

"He had this charm about him,” said Pozner. “He was handsome. He was incredibly loving."

But that morning, on Dec. 14, 2012, Adam Lanza walked into Sandy Hook and gunned down Noah, along with 19 other children and six staff members.

"I feel like I really only had a year or two with him where he wasn’t Noah the toddler or Noah the baby, but was Noah the person.”

While Pozner and his family must live with their loss of Noah every day, there is another story circulating the Internet, and it often comes in the form of slanderous remarks and even death threats against the Pozner family:

Noah never existed. Pozner is an actor, paid to perpetuate a massive hoax staged by the government and the media to build support for gun control.

One man told Pozner he should “be put in boiling feces.”

A memorial for Noah Pozner outside his funeral in Fairfield, Conn., on Dec. 17, 2012.(Photo11: Robert Deutsch, USA TODAY)

Others have insisted that he and other Sandy Hook parents exhume the bodies of their children to prove they existed.

On Dec. 5, federal agents arrested Lucy Richards, 57, of Tampa, believing her to be the woman who has been leaving voicemails on Pozner’s phone, saying, “You gonna die, death is coming to you real soon,” and “Look behind you, it is death.”

This is what fake news fuels, Pozner said.

“You’ll never be able to convince these people of anything," Pozner said.

The Internet, he said, is a great equalizer that gives an equal voice to a lie and the truth. When enough people believe the same lie, it spreads like a "thought virus."

But Richards’ arrest shows there is a limit to what people can say, Pozner said.

“It shows that, yes, there is a threshold.”

Wednesday marked the fourth anniversary of the Sandy Hook shooting.

For most of that time, Pozner, who said he once held conspiracy theorist views of his own, has been confronting lies and false stories about the massacre that have been spread through an echo chamber over the Internet.

He started by confronting the conspiracy theorists themselves, joining Facebook pages dedicated to proving that his son's murder was a hoax and answering the group’s questions. He spoke with “hoaxers” over the phone and by email.

A mourner walks into a funeral service for 6-year-old Noah Pozner on Dec. 17, 2012, in Fairfield, Conn.(Photo11: Jason DeCrow, AP)

But he said it didn’t work.

When skeptics demanded his son’s birth certificate, Pozner published it. When they asked for Noah’s kindergarten progress reports, Pozner produced them. Hardest of all, when they asked for his death certificate, Pozner, after weeks of struggling, posted a copy online.

They didn’t read Noah’s report card and see that his kindergarten teacher had included a note saying that he was a sweet, inquisitive boy she would miss having in her class. They didn’t take note that he was born a healthy 7 pounds, 2 ounces. They weren’t moved by the death certificate that said he was found lying on his back in his classroom, wearing his red and black Spider-Man sweatshirt, with wounds around his mouth and chin.

“They’d find a typo or spelling error and pick it apart,” Pozner said. “They needed to claim it was fake because it would shut down all their theories. They’d point to variations in typefaces and fonts.”

In 2015, Pozner decided that he couldn’t hold the hands of conspiracy theorists and convince them of the truth. He shifted his focus to taking away their platforms, trying to flag content and convince Silicon Valley behemoths like Facebook, Twitter, Google and YouTube to remove their videos and articles online. He created the HONR Network, a team of volunteers dedicated to flagging content that crosses over into slander and attacks, one at a time.

“This online hoaxer world is pretty large,” Pozner said. “I’ve been saying for years that it’s like this brush fire that’s ready to burn down the entire forest. It’s starting to rot out the Internet at the core. This online hate does lead to violence and murder.”

He said he is starting to see progress.

The world, at least, is becoming more aware of the violence that can be caused by rumors, lies and false stories spread online.

On Dec. 4, Edgar Maddison Welch, a 28-year-old North Carolina man, walked into the Comet Ping Pong pizzeria in Washington, D.C., with an AR-15 rifle and opened fire as employees ran for cover. According to D.C. Metro Police, Welch told them he was there to investigate a fictitious online conspiracy that the pizza parlor was a front for a child sex ring operated by former Democratic presidential candidate Hillary Clinton.

“Lawmakers and police aren’t tuned into this,” Pozner said. “They weren’t in school when this stuff existed. It’s not on their radar until somebody shows up to a pizzeria and unloads bullets.”

Pozner said he has no doubt that he needs to continue confronting the spread of conspiracies and fake news.

It’s the only way, he said, he can protect his son’s memory.

Noah was born on Nov. 20. This year, Pozner bought a few balloons in Noah's name. He wanted to do something very little, he said, because it’s a complicated day.

Noah has a twin sister.

“I felt so bad in 2013 because we didn’t properly celebrate our daughter’s birthday,” he said. “It brought us down. I tried really hard this year to focus on her good day. We might have celebrated it twice as much to make up for it.”